My recent posts have focused on oxidative stress, free radicals, and antioxidants. But they haven’t identified what foods are high in antioxidants. The answer to this question isn’t straightforward , for two reasons.
First, not all dietary antioxidants appear to be helpful. What’s even more concerning is that on entering our bodies, some of them become harmful pro–oxidants.
Take the findings of 2014 study published in Molecular and Cellular Biochemistry that in certain situations, “some antioxidants can also exhibit pro-oxidant mechanism in action.”
In other research, a team of international pharmaceutical experts reviewed the most popular antioxidant vitamins. They found a mixed bag of benefits and drawbacks.
Some readers may view this study (seen here) as alarming:
- The antioxidant Vitamin E protects against lipid (fat) peroxidation. Still, a meta-analysis of people taking vitamin E supplements found that taking more than 400 IU/d a day “may increase all-cause mortality.”
- Taking more than 2000mg per day of the antioxidant Vitamin C is potentially carcinogenic. It may also cause pro-oxidant activity.
- Beta -carotene, a potent antioxidant and the “best quencher of singlet oxygen,” may be a poor choice for habitual smokers.
Those who took 20-30 mg of beta-carotene daily while avoiding beta-carotene-rich foods had a 12- to 26-percent higher rate of cardiovascular mortality and higher risks of lung and prostate cancers.
- Although the antioxidant lycopene is “very protective” against prostate cancer, its “anticancer activity in humans remains controversial.”
- Selenium’s antioxidant properties have yielded “mixed” results in various rials.
But none of the above is food. They’re vitamin and mineral supplements – a little fact that seems to make a huge difference!
Supplements aren’t great antioxidant sources because antioxidants are most helpful when they act with the other nutrients naturally found in fruits, vegetables, herbs, and spices.
Teamwork enables them to move from our mouths to the places in our bodies where they connect with the correct free radicals. So, which ingredients are best?
What Foods Are High in Antioxidants and Helpful?
This published list from 2010 identifies the antioxidant levels of 3,100 foods. I could easily just name its highest-ranked ingredients, such as amla and cloves.
Indeed, the Internet is home to thousands of lists telling us what foods are high in antioxidants – and nearly all include dark chocolate and a variety of berries.
But the University of Oslo researchers who created the 3100-food list analyzed their antioxidant content using the FRAP assay. The FRAP assay and these similar tests may produce misleading results:
My past posts have mentioned FRAP and ORAC scores. Unfortunately, while their antioxidant measurements might be accurate, they don’t necessarily paint a clear picture.
Just as supplements aren’t reliable antioxidant sources, the antioxidant-measuring tools raised questions. Why? Because they don’t correlate a food’s antioxidant content with its helpful effects in our bodies!
It doesn’t matter what foods are high in antioxidants if the antioxidants pass directly through our digestive tracts and into the toilet! Such was the concern of the authors of this Rutgers University Department of Food Sciences study:
“Most antioxidants are poorly absorbed or are rapidly conjugated and eliminated in the urine, so circulating phenol concentrations reach trace levels at best.”
Not only that, but the “trace levels” that do reach the free radicals may be unhelpful in scavenging them!
In 2010, the USDA abandoned the ORAC values they’d long used to determine antioxidant levels and posted this explanation:
“There is no evidence that the beneficial effects of polyphenol-rich foods can be attributed to [their] antioxidant properties… antioxidant capacity of foods generated by… (test-tube) methods cannot be extrapolated to… (human) effects….”
[A]ntioxidant[s]… have a wide range of functions… unrelated to the ability to absorb free radicals. For these reasons, the ORAC table previously available on this website has been withdrawn.”
How Antioxidants Act Against Free Radicals
The USDA realized that a food’s antioxidant score had little bearing on the degree of its nutrients’ activity in neutralizing free radicals.
The logical reason for this discrepancy is that a food’s other nutrients act in tandem with the antioxidants, giving every whole-food nutrient equal health-protective importance!
We know that plant-based foods are generally high in antioxidants and powerful reducers of oxidative stress. However, isolating the effective antioxidants in different foods has often proved elusive.
The latest Redox Biology Journal published a systematic review on how a person’s diet impacts oxidative stress and inflammation. Strong evidence led to its conclusion that “plant-based dietary patterns” decrease both conditions.
And I wholeheartedly agree: The answer to “What foods are high in antioxidants?” is simply, “Plant-based foods!”
Until science gives us a better answer, consuming a variety of plant-based foods raises our antioxidant intake, effectively counterbalances free radicals, and minimizes oxidative stress!